This invention relates generally to a rodent cage which may be used as a static unit or in connection with a ventilated cage and rack system for housing a variety of rodent types and in particular to a filter top for such a cage.
Ventilated cage and rack systems are well known in the art. One such ventilated cage and rack system is disclosed in U.S. Pat. No. 4,989,545, assigned to Lab Products, Inc., in which an open rack system including a plurality of shelves, each formed as an air plenum is provided. A ventilation system is connected to the rack system for ventilating each cage in the rack. It is known to house rats for study in such a ventilated cage and rack system.
Filter tops for animal cages within ventilated cage and rack systems are also well-known in the art. One such filter top is disclosed in U.S. Pat. No. 4,640,228, assigned to Lab Products, Inc. in which a bonnet with a perforated top wall is provided. A sheet of filter paper is sandwiched between the retainer and the lower surface of the perforated top wall of the bonnet. A retainer is detachably mounted inside the bonnet body in flush abutment with the filter material placed against the lower surface of the top wall of the bonnet the retainer comprises a narrow border portion and flat cross arms which intersect at an integral central portion.
Accordingly it is desired to provide a filter cage top for a cage which protects the filter and cage top while being easy to clean.